Any way to put Residential Only objects on a Community Lot?
I mean a Community Lot that isn't Owned.

Tried switching between using the Zoning mod
but everything gets erased.

Would like to build a Car Museum.

Everything but real cars should stay. Meaning if any other residential item vanished you have an issue, but working cars do vanish unless the lot is owned.

Correct, I could have written it that way.

The only solution I can think of is using SimPE to modify the objects you want so they'll be available on community lots. Take a look here: http://www.insimenator.org/index.php?topic=112336.0

I don't know whether Sims might attempt to use the cars and whether that would cause issues, but you could always block them off using a fence/invisible fence.

Another option would be to make a deco-only clone of the cars you want so you can use them like sculptures, or downloading deco cars.

Cars that are on the car display stand are okay, aren't they? You don't have to actually sell them.

Forgot about that. Will try it, but Optimism is Low.
When poking around I found this:

While the display can be placed on an unowned community lot,
cars cannot be purchased on community lots until Wholesale mode is enabled.
A car dealership, as such, cannot be run from an unowned community lot,
and can only be stocked on owned community lots.

Figgered out a very roundabout way go have an Unowned Car Lot.
Not exactly what I Wanted, but there is a Result.

-Cheat a Sim into being very wealthy
-Build & buy them the Fancy Car Show or Museum Lot
-Then Sell the whole thing Back to the Community Real Estate.

The Cars Will Stick in Place.
Can't add any Cars after selling, but it will work as regular Community Lot.

Damn. Didn't know that cars couldn't be bought.

I guess you'll have to have a wealthy philanthropist who donates their collection to a museum.